Energy Production Of An Efficient Integration Two-stage Anaerobic Bioreactor By Using Alage

Using biotechnology to ferment algae can achieve resource productivity while processing algae waste.However,the current algae biological fermentation has the disadvantages of low substrate utilization,poor productivity and slow fermentation speed,which hinders algae anaerobic fermentation Industrialization and scale of production capacity.In view of these problems,this study used an integrated two-phase anaerobic fermentation reactor combined with a continuous stirred reactor(CSTR)and an upflow anaerobic sludge bed reactor(UASB)to study the algae fermentation capacity.The effects of pretreatment of metal nanoparticles and substrates on the anaerobic fermentation of algae when used alone and in combination were studied through static experiments.The results show that the addition of metal nanoparticles and substrate pretreatment can effectively increase the hydrolysis rate,speed up the fermentation process and increase gas production capacity.The combined use of metal nanoparticles and substrate pretreatment can obtain better fermentation effect than using alone.When the concentration of nickel nanoparticles(Ni NPs)is 1 mg/L,the liquid-solid ratio is 20:1,and the microwave power is 400 W for 5 minutes,the highest hydrogen production is 483 m L(29.0 m L/g COD)and the highest energy efficiency.Ratio(1.18).Taking industrial glucose as the substrate because it is easier to digest.the initial COD content in the feedwater is 3000 mg/L,the total organic load of the system is 2 kg/(m~3·d),and the hydraulic retention time(HRT)is 60 h(production Under the conditions of acidic phase 10 h and methanogenic phase 50 h),the start-up of the two-phase anaerobic fermentation reactor was completed at 39 d by a stepwise starting method.After that,the start-up of the two-phase anaerobic fermentation system with algae as the sole substrate was completed at 103 d by means of load lifting and substrate replacement.At this time,the optimal total organic load(Nv)of the system operation,the organic load(Nv)of the acid-producing phase and the methanogenic phase were 4,24,and 4.8 kg/(m3·d),respectively;the system’s hydrogen production and methane production The energy efficiency ratio of the system is 1.12 at 5.6 L/d(28.0 m L/g COD)and 27.3 L/d(136.5 m L/g COD).The high-throughput sequencing method was used to study the changes of microbial community structure in the acid-producing phase during the startup process.The results showed that the relative abundance of microorganisms related to anaerobic fermentation such as Clostridia,Actinomycetes and Bacteroides was significantly increased during the start-up process,indicating that the stepwise start-up method of this experiment can be cultured in the acid-producing phase.A microbial population with a complete fermentation function is produced.Keeping the operating conditions unchanged,Ni NPs were added to the acid-producing phase of the continuous flow reaction system to further investigate the promotion effect of metal nanoparticles on anaerobic fermentation.The reactors were operated for more than 10 d when the system feed Ni NPs were 0.75,1 and 1.25 mg/L,respectively.When the amount of Ni NPs was 1 mg/L,the anaerobic fermentation system had the most hydrogen production of7.3 L/d(30.5 m L/g COD)and the most methane production of 36.2 L/d(151.0 m L/g COD),and the highest efficiency ratio of 1.35.The results show that the metal nanoparticle combined substrate pretreatment method is practically feasible for a two-phase anaerobic fermentation process using algae as a substrate,and is a promising algae biological treatment process.